Clin Res Cardiol (2022). https://doi.org/10.1007/s00392-022-02002-5

Cardiac SARS-CoV-2 infection is associated with pro-inflammatory transcriptomic alterations within the heart

H. Bräuninger1, B. Stoffers1, A. Fitzek2, K. Meißner2, G. Aleshcheva3, J. Weimann1, S. Warnke1, C. Edler2, K. Scherschel4, F. Escher5, S. Kluge6, T. B. Huber7, B. Ondruschka2, H.-P. Schultheiss3, P. Kirchhof1, S. Blankenberg1, K. Püschel2, D. Lindner1, D. Westermann1

1Klinik für Kardiologie, Universitäres Herz- und Gefäßzentrum Hamburg GmbH, Hamburg; 2Institut für Rechtsmedizin, Universitätsklinikum Hamburg-Eppendorf, Hamburg; 3IKDT - Institut Kardiale Diagnostik und Therapie GmbH, Berlin; 4Klinik für Kardiologie, Evangelisches Krankenhaus Düsseldorf, Düsseldorf; 5CC11: Med. Klinik m.S. Kardiologie, Charité - Universitätsmedizin Berlin, Berlin; 6Klinik für Intensivmedizin, Universitätsklinkum Hamburg-Eppendorf, Hamburg; 7III. Medizinische Klinik, Universitätsklinikum Hamburg-Eppendorf, Hamburg;

Background: Cardiac involvement in COVID-19 is associated with adverse outcome. Furthermore, a previous study from our group showed viral RNA in heart tissue in 41% of SARS-CoV-2 deceased. To what extend direct cardiac infection of SARS-CoV-2 is leading to inflammation and immune response is still unclear. Therefore, the aim of this study was to unveil pathophysiological consequences of direct cardiac SARS-CoV-2 infection. Methods: We examined cardiac tissue from 95 COVID-19 autopsy cases and detected viral RNA in 43% of deceased. Thus, we compared cases with and without cardiac infection by bulk RNA-sequencing (10 cases with and 10 cases without cardiac infection) and by histological analysis to identify differentially expressed genes, immune cell infiltration and targeted cell types. Based on the RNA-sequencing results, we performed digital cytometry and GO enrichment analysis. Results: Using bulk RNA-Sequencing, 824 genes with a p-value <0.05 and 19 genes with a q-value <0.05 were detected. The sequencing results were used to estimate cell fractions in the cardiac tissue of cases with and without cardiac infection by digital cytometry. For this purpose, a signature matrix out of the single-cell RNA-sequencing dataset “heart cell atlas” was built with the help of CibersortX. Regarding immune cell infiltration, lymphoid (7.8 ± 1.3% vs. 8.8 ± 1.8%; P=0.6854) and myeloid cell fractions (4.3 ± 0.6% vs. 4.9 ± 0.8%; P=0.6140) did not differ between the groups with and without cardiac infection. Additionally, immune cell infiltrates were quantified by diagnostic immunohistochemistry in all 95 cases. The number of infiltrated cells was compared between cases with and without cardiac infection. No significant differences were determined for CD45R0+ (P=0.61), CD3+ (P=0.17) and CD68+ (P=0.30) between both groups. Furthermore, based on the RNA-sequencing results, GO term enrichment analysis was performed and revealed 188 significantly regulated GO terms (q value <0.05). Ten most relevant GO terms with at least 20% regulated genes and a q-value <0.001 were identified. Five out of ten were linked to anti-virus immune response, all of them comprising mainly upregulated genes. The other five most relevant GO terms comprised mainly downregulated genes and were cardiomyocyte-specific. To unveil the cardiac cell type infected by SARS-CoV-2, we performed in situ hybridization to visualize viral RNA and immunofluorescence staining to detect viral nuclear protein. A co-staining of viral protein and ICAM1, an endothelial cell marker, revealed endothelial cells as the main target cell type of SARS-CoV-2. In contrast, co-localization with the cardiomyocyte marker alpha-actinin and the viral protein was observed in very few cases. Conclusion: SARS-CoV-2 induces pro-inflammatory transcriptomic alterations by direct infection of the myocardium. Our findings provide new insights about cell-specific consequences of cardiac infection. While cardiomyocytes do not seem to be the main target of SARS-CoV-2, cardiomyocyte-specific GO terms were downregulated, suggesting negative paracrine effects. In contrast, SARS-CoV-2 infected endothelial cells were detected frequently.

https://dgk.org/kongress_programme/jt2022/aV916.html